Rotary compressor

ABSTRACT

An oil hole is formed in a thrust-bearing surface in the eccentric part of a rotary shaft so that a given amount of lubricating oil is always maintained in the oil hole, whereby shortage of oil does not occur at the time of restarting of the rotary compressor after a long term pause of the operation.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a rotary compressor having alubricating oil supplying device. More particularly, it relates to animprovement in feeding of oil to a thrust-bearing surface which is inslide-contact with an eccentric part of a rotary shaft.

2. Description of Prior Art

FIG. 1 is a cross-sectional view of an important part of a conventionalrotary compressor as disclosed in Japanese Unexamined Patent PublicationNo. 106089/1981.

In FIG. 1, a reference numeral 1 designates a cylinder and a numeral 2designates a rotary shaft which is adapted to be rotated in the cylinderand having an eccentric part 3 formed integrally with it. The rotaryshaft is driven by a motor (not shown) provided at the upper side on thedrawing. A rolling piston 4 is fitted on the outer circumferentialsurface of the eccentric part 3 to eccentrically rotate in the cylinder1 in accordance with the rotation of the rotary shaft. A referencenumeral 5 designates a main bearing plate for supporting a part of therotary shaft 2 extending toward the motor and a numeral 6 designates asub-bearing plate for supporting a part of the rotary shaft 2 extendingin the direction opposite the motor with respect to the eccentric part3, both the bearing plates being placed at both sides of the cylinder 1to keep the inside of the cylinder in a hermetic condition. A numeral 7designates vanes whose extreme ends are usually in contact with therolling piston 4 under a desired pressure applied by means ofcompression springs, a numeral 8 designates a thrust-bearing surfaceformed between the eccentric part 3 and the sub-bearing plate 6, asymbol A designates a conduit formed in the axial center portion of therotary shaft 2 to feed lubricating oil for circulation in the compressordevice, a symbol a indicates oil feeding passages formed in the rotaryshaft 2 in the radial direction from the conduit, and a symbol Bindicates a compression chamber.

In the conventional rotary compressor having the construction asabove-mentioned, there is a disadvantage such that since there is nofacility to keep the lubricating oil in the thrust-bearing surface, whenthe compressor is to be re-started after the operation of the compressorhas been paused for a long term, there arises a shortage of oil in thethrust-bearing surface 8, with the result that friction in thethrust-bearing surface frequently occurs, whereby much input power isrequired at the time of restarting of the compressor.

SUMMARY OF THE INVENTION

It is an object of the present invention to eliminate the disadvantageof the conventional rotary compressor and to provide an improved rotarycompressor free from shortage of lubricating oil at restarting timeafter a long term pause of operation.

The foregoing and the other objects of the present invention have beenattained by providing a rotary compressor which comprises a cylinder, arotary shaft having an eccentric part, and a pair of bearing plateswhich close hermetically both open ends formed in the cylinder androtatably support the rotary shaft, the rotary compressor including alubricating oil supplying device in which an oil hole is formed in atleast one end surface of the eccentric part being in slide-contact withthe bearing plates so as to store lubricating oil circulating inside therotary compressor.

BRIEF DESCRIPTION OF DRAWING

FIG. 1 is a cross-sectional view of an important part of a conventionalrotary compressor;

FIG. 2 is a cross-sectional view of an important part of a firstembodiment of the rotary compressor according to the present invention;

FIG. 3 is a cross-sectional view of a second embodiment of the presentinvention; and

FIG. 4 is a cross-sectional view of a third embodiment of the presentinvention

DETAILED DESCRIPTION OF PREFFERED EMBODIMENTS

FIGS. 2 to 4 show the first to the third embodiments of the presentinvention in which the same reference numerals as in FIG. 1 designatethe same or corresponding parts and therefore, description of theseparts is omitted.

In the first embodiment of the present invention shown in FIG. 2,isolated oil hole 9 is formed in the eccentric part 3 so as to open inthe thrust-bearing surface 8 formed between the eccentric part 3 and thesub-bearing plate 6 placed opposing the motor with respect to theeccentric part 3. The oil hole 9 can maintain a predetermined amount oflubricating oil. Accordingly, shortage of oil in the thrust-bearingsurface 8 which may occur at the restarting of the rotary compressor canbe eliminated.

Generally, the rotary compressor of the present invention is used underthe condition that the rotary shaft 2 extends in the vertical direction.In this case, the main bearing plate 5 functions as an upper bearingplate to rotatably support the upper part of the rotary shaft 2, and thesub-bearing plate 6 functions as a lower bearing plate.

Since the oil hole 9 is formed in the eccentric part 3 to open thethrust-bearing surface 8 in a form of recess, the lubricating oilsuppled to the thrust-bearing surface 8 during the operation of therotary compressor is stored in the recessed oil hole 9, thus supply ofoil to the oil hole 9 is carried out.

In the second embodiment of the present invention shown in FIG. 3, theoil hole 9 is a through hole extending and opening in the boththrust-bearing surfaces formed between the main bearing plate 5 and theeccentric part 3 and the sub-bearing plate 6 and the eccentric part 3.With the construction of the second embodiment, the capacity of holdingthe lubricating oil can be further increased in comparison with thefirst embodiment and therefore, it is flexible to change in condition ofthe thrust-bearing surface. The second embodiment is particularlyeffective in the case the thrust-bearing surface is also formed betweenthe main bearing plate 5 and the eccentric part 3.

FIG. 4 shows the third embodiment of the present invention. The oil holeis formed extending both end surfaces of the eccentric part 3, and achamfered part 6a is formed in the sub-bearing plate so that the oilhole 9 is communicated with one of oil feeding passages a formed in theradial direction in the rotary shaft 2. Accordingly, the lubricating oilstored in the oil hole 9 is well circulated to control temperature risein the lubricating oil, whereby reduction in lubricating characteristicof the oil due to temperature rise is avoidable.

In the third embodiment, when the compressor is stopped, the lubricatingoil flows out the oil hole 9. However, immediately after restarting ofthe operation of the compressor, oil supply is initiated to thethrust-bearing surface 8 from the conduit A through the two oil feedingpassages a, a, the chamfered part 6a and the oil hole 9. Accordingly,shortage of oil will not take place.

In the foregoing, description has been made as to formation of thethrust-bearing surface between the eccentric part and the sub-bearingplate. However, it is feasible that the thrust-bearing surface is formedbetween the main bearing plate and the eccentric part.

Thus, an oil hole for lubricating oil is formed in a thrust-bearingsurface with respect to an eccentric part formed in a rotary shaft,shortage of oil in the thrust-bearing surface which may occur at therestarting time of the rotary compressor after a pause of operation canbe avoided. This remarkably increase reliability in the thrust-bearingpart. Further, the oil hole is communicated with an oil feeding passageformed in the rotary shaft in the radial direction, whereby ability offeeding the lubricating oil to the oil hole during normal operation ofthe rotary compressor is increased. The increased ability of oil feedingsupresses temperature rise in the lubricating oil to be circulated inthe rotary compressor, and reduction in lubricating characteristic dueto temperature rise can be certainly prevented.

What is claimed is:
 1. A rotary compressor comprising:means defining acylinder and bearing plates closing opposite ends of said cylinder; arotary shaft extending through said cylinder along a vertical axisparallel to the axis of said cylinder; an eccentric part in saidcylinder and fixed to said shaft, at least a bottom end surface of saideccentric part being in slide bearing contact with one of said bearingplates; and lubricating oil supplying means comprising: (a) an oil holeextending in said eccentric part from said bottom axial end face of saideccentric part to a top axial end face of said eccentric part, (b) anaxially extending oil feeding conduit in said shaft, (c) radiallyextending oil feeding passage means connecting said oil feeding conduitto said bearing plates for lubricating said bearing plates, (d) firstmeans for communicating said oil hole with said passage means connectingsaid oil feeding conduit with another of said bearing plates in bearingcontact with said top axial end face of said eccentric part, and (e)second means for communicating said oil hole with said passage meansconnecting said oil feeding conduit with said one of said bearingplates, whereby oil circulation through said hole is improved, whereinsaid second means for communicating comprises a chamfer formed in saidone bearing plate.